Step-and-Flash Imprint Lithography (S-FIL(TM)) is a one-to-one imprinting process in which features are transferred from a template by lowering it onto a low-viscosity, photocurable, monomer solution that conforms to the template surface and is subsequently cured. The potential exists for both low cost and high throughput, making S-FIL a promising candidate for Next-Generation Lithography. However, there are many challenges that must be overcome in order to ensure the future viability of S-FIL. Mechanical distortion control is one of the principal challenges, and is addressed in this article. During the imprinting process, the viscous flow of the monomer liquid causes a significant pressure elevation within the fluid as it is forced to flow outwards through a small gap. These pressures cause out-of-plane distortions and in-plane distortions (OPD and IPD) of the template, which may be manifested as errors in the replicated pattern. A fluid-structure model was developed to predict the template distortion associated with the imprinting process. The model consists of two parts. The Reynolds Equation Module (REM) is a two-dimensional finite-difference model that solves the Reynolds equation, which describes the laminar flow of an incompressible constant-viscosity fluid through a small gap. The pressure distribution predicted by the REM is applied as a structural load, together with vacuum chucking and gravity, to a finite-element model of the template developed using ANSYS(R). This model, called the, Structural Distortion Model, calculates the resulting OPD and IPD of the template. The process is iterated in time for a continually decreasing gap height that corresponds to lowering the template. This article presents the details of the fluid-structure model, the results of the analysis at nominal conditions, and a parametric study of the effects of the operating conditions and fluid properties on the template distortion. (C) 2004 American Vacuum Society.